1. Field of the Invention
The present invention relates to an image forming apparatus.
2. Description of the Related Art
An image forming apparatus which uses an electrophotographic method, such as a copying machine, printer, facsimile machine, or a multifunction peripheral of these, for example, a photosensitive drum, which is an image carrier, a charging device for uniformly charging the circumferential surface of the photosensitive drum, an exposure device for forming an electrostatic latent image based on image data on the photosensitive drum, a developing device for developing an electrostatic latent image on the photosensitive drum, into a toner image, and a transfer device for transferring the toner image on the photosensitive drum onto a recording medium, such as paper, via an intermediate transfer belt, or the like.
The charging device used in an image forming apparatus of this kind may be, for example, a charging device based on a contact charging method or a charging device based on a non-contact charging method. It is known that charging devices based on a contact charging method can suppress the generation of ozone compared to a charging device based on a non-contact charging method.
Furthermore, one example of a charging device using a contact charging method is a device comprising a charging roller such as that described below, for instance. A more specific example is a charging roller used in an electrophotographic apparatus employing a two-component toner, the roller comprising a shaft body, a base rubber layer formed on the outer circumference of the shaft body, and a surface layer formed directly or via another layer on the outer circumference of the base rubber layer, wherein the base rubber layer is made of a base rubber layer forming material of which the main component is rubber having a JIS-A hardness of 15° or lower, and the surface layer is made of a surface forming material having an elongation (Eb) based on JIS K6251 of 5 to 90%, and a tensile strength (TS) of no less than 35 MPa.